I’m assuming you are referring to the show Friends. If that’s the case you don’t have to worry about a copyright infringement as a you can’t copyright a theme. If you were to paint the script from particular episodes on your walls you may have an issue. Also, you could run into problems with the right of publicity if the characters or the show matter are used directly to enhance the theme of your cafe.
You should probably seek the opinion of an attorney before you carry on with your plan. My companyroutinely connects small businesses with skilled IP / business attorneys so that the legal component of their companies can be a strength, not a weakness.